Robust polyaniline coated microcapsules with superior thermal and solvent stability

For a microcapsule, the efficient encapsulation and retention of active ingredients as well as sufficient mechanical property is very important in many practical applications, which is still a challenging task and remains unsolved. In this work, a novel kind of polyaniline-coated microcapsule with outstanding strength, superior thermal and solvent stability was developed. In our strategy, a sulfonated polyacrylate microcapsule was firstly prepared via photopolymerization, and a dense and uniform polyaniline (PANI) layer was then applied to sulfonated microcapsule surfaces via the polymerization of aniline monomer. The presence of PANI layer prevented loss of encapsulated oil and remarkably enhanced microcapsule stability in various organic solvents which otherwise resulted in deflation and core loss of uncoated microcapsules. Compared to the uncoated shell, the PANI-coated shell postponed the beginning mass loss temperature of the microcapsule by about 100 °C. After isothermal treatment at 250 °C for 60 min, PANI-coated microcapsules exhibited only 4.5% weight loss, much lower compared with 58.2% weight loss of the uncoated microcapsule, demonstrating good core retention ability at high temperatures. In the meanwhile, the mechanical performance of the resulted PANI-coated microcapsules has also been remarkably enhanced. The Young's modulus and hardness of the PANI-coated microcapsules was 4 times and 9 times that of uncoated microcapsules.